A treatise on surveying, comprising the theory and the practice ; (1887)
Gillespie, W. M. (William Mitchell), 1816-1868, Staley, Cady, 1840- [from old catalog] ed · New York, D. Appleton and company · leaf 469
o the signal-staff, which passesthrough it, is a cheap and good arrangement. A tuft of pine-boughs fastened to the top of the staff will be well seen against thesky. In sunshine a number of pieces of tin, nailed to the staff atdifferent angles, will be very conspicuous. A truncated cone ofburnished… … scope, near the eye-end, that the reflection of the sun may bethrown in any desired direction. They have been observed on at adistance of nearly two hundred miles, when the outlines of themountains on which they were placed were invisible. A man,called a heliotroper, is stationed at the instrument.…
Surveying
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